High power radiation emitter device and heat dissipating package for electronic components

ABSTRACT

The electronic component package ( 10 ) of the present invention includes a sealed chamber, a liquid or gel ( 20 ) contained in the sealed chamber, at least one electronic component ( 12 ) disposed in the sealed chamber in physical and thermal contact with the liquid or gel ( 20 ); and at least one electrical conductor electrically coupled to the electronic component and extending out of the sealed chamber. The electronic component(s) ( 12 ) may include any one or combination of a radiation emitter, a thermal or optical sensor, a resistor, and a microprocessor or other semiconductor component.

BACKGROUND OF THE INVENTION

[0001] The present invention generally relates to radiation emitterassemblies such as, for example, light emitting diode (LED) packages andto heat dissipating packages for electronic components.

[0002] Radiation emitters, particularly optical radiation emitters, areused in a wide variety of commercial and industrial products and systemsand accordingly come in many forms and packages. As used herein, theterm “optical radiation emitter” includes all emitter devices that emitvisible light, near infrared (IR) radiation, and ultraviolet (UV)radiation. Such optical radiation emitters may be photoluminescent,electroluminescent, or other solid state emitter. Photoluminescentsources include phosphorescent and fluorescent sources. Fluorescentsources include phosphors and fluorescent dyes, pigments, crystals,substrates, coatings, and other materials.

[0003] Electroluminescent sources include semiconductor opticalradiation emitters and other devices that emit optical radiation inresponse to electrical excitation. Semiconductor optical radiationemitters include light emitting diode (LED) chips, light emittingpolymers (LEPs), organic light emitting devices (OLEDs), polymer lightemitting devices (PLEDs), etc.

[0004] Semiconductor optical emitter components, particularly LEDdevices, have become commonplace in a wide variety of consumer andindustrial optoelectronic applications. Other types of semiconductoroptical emitter components, including OLEDs, LEPs, and the like, mayalso be packaged in discrete components suitable as substitutes forconventional inorganic LEDs in many of these applications.

[0005] Visible LED components of all colors are used alone or in smallclusters as status indicators on such products as computer monitors,coffee makers, stereo receivers, CD players, VCRs, and the like. Suchindicators are also found in a diversity of systems such as instrumentpanels in aircraft, trains, ships, cars, trucks, minivans and sportutility vehicles, etc. Addressable arrays containing hundreds orthousands of visible LED components are found in moving-message displayssuch as those found in many airports and stock market trading centersand also as high brightness large-area outdoor television screens foundin many sports complexes and on some urban billboards.

[0006] Amber, red, and red-orange emitting visible LEDs are used inarrays of up to 100 components in visual signaling systems such asvehicle center high mounted stop lamps (CHMSLs), brake lamps, exteriorturn signals and hazard flashers, exterior signaling mirrors, and forroadway construction hazard markers. Amber, red, and blue-green emittingvisible LEDs are increasingly being used in much larger arrays of up to300 components as stop/slow/go lights at intersections in urban andsuburban intersections.

[0007] Multi-color combinations of pluralities of visible colored LEDsare being used as the source of projected white light for illuminationin binary-complementary and ternary RGB illuminators. Such illuminatorsare useful as vehicle or aircraft maplights, for example, or as vehicleor aircraft reading or courtesy lights, cargo lights, license plateilluminators, backup lights, and exterior mirror puddle lights. Otherpertinent uses include portable flashlights and other illuminatorapplications where rugged, compact, lightweight, high efficiency,long-life, low voltage sources of white illumination are needed.Phosphor-enhanced “white” LEDs may also be used in some of theseinstances as illuminators.

[0008] IR emitting LEDs are being used for remote control andcommunication in such devices as VCR, TV, CD, and other audio-visualremote control units. Similarly, high intensity IR-emitting LEDs arebeing used for communication between IRDA devices such as desktop,laptop and palmtop computers; PDAs (personal digital assistants); andcomputer peripherals such as printers, network adapters, pointingdevices (“mice,” trackballs, etc.), keyboards, and other computers. IRLED emitters and IR receivers also serve as sensors for proximity orpresence in industrial control systems, for location or orientationwithin such opto-electronic devices such as pointing devices and opticalencoders, and as read heads in such systems as barcode scanners. IR LEDemitters may also be used in a night vision system for automobiles.

[0009] Blue, violet, and UV emitting LEDs and LED lasers are being usedextensively for data storage and retrieval applications such as readingand writing to high-density optical storage disks.

[0010] Performance and reliability of LED components, chips, and systemsare heavily influenced by the thermal performance of those components,chips, and systems, and by ambient temperature. Elevated operatingtemperatures simultaneously reduce the emission efficiency of LEDs andincrease the probability of failure in most conditions. This elevatedtemperature may be the result of high system thermal resistance actingin concert with internal LED power dissipation and may also be theresult of high ambient operating temperature or other influence.Regardless of the cause, LED efficiency and reliability are normaladversely affected by increases in temperature. Thus, it is advantageousto minimize temperature rise of LED components, chips, and systemsattributable to internal power dissipation during operation. This can beaccomplished by reducing the conductive, convective, and radiativethermal resistance between the LED chip and ambient environment, such asby optimizing the materials and construction of the packaged devicecontaining the LED chip. These methods, as applicable tomass-solderable, auto-insertable, and other discrete LED components, aredisclosed in commonly assigned U.S. Pat. No. 6,335,548, entitled“SEMICONDUCTOR RADIATION EMITTER PACKAGE,” filed on Oct. 22, 1999, byJohn K. Roberts et al., and published PCT International Publication No.WO 00/55914.

[0011] For high power LED systems and high power density LED systems,system thermal performance is especially critical. LED illuminators andhigh power signal lights generating more than ten lumens (or more thanone watt of power dissipation) are examples of systems which can benefitfrom improved thermal performance, especially if package area/volumemust be minimized (increasing power density).

[0012] To limit the operational temperature of the LED, the power thatis allowed to be dissipated through the LED is typically limited. Tolimit the dissipated power, however, the current that may be passedthrough the LED must be limited, which in turn limits the emitted fluxof the LED since the emitted flux is typically proportional to theelectrical current passed through the LED.

[0013] Other fundamental properties of LEDs place further restrictionson the useful operational temperature change AT. Semiconductor LEDs,including IR, visible, and UV emitters, emit light via the physicalmechanism of electro-luminescence. Their emission is characteristic ofthe band gap of the materials from which they are composed and theirquantum efficiency varies inversely with their internal temperature. Anincrease in LED chip temperature results in a corresponding decrease intheir emission efficiency. This effect is quite significant for allcommon types of LEDs for visible, UV, and IR emission. Commonly, a 1° C.increase (ΔT) in chip temperature typically results in up to a 1 percentreduction in useful radiation and up to a 0.1 nm shift in the peakwavelength of the emission, assuming operation at a constant power.Thus, a ΔT of 40° C. can result in up to a 40 percent reduction inemitted flux and a 4 nm shift in peak wavelength.

[0014] From the preceding discussion, it can be seen that to avoidthermal damage and achieve optimal LED emission performance, it is veryimportant to minimize the ΔT experienced by the LED device chip andpackage during operation. This may be achieved by limiting power orreducing thermal resistance.

[0015] Limiting LED power, of course, is antithetical to the purpose ofhigh power LEDs, i.e., to produce more useful radiation. Generatinghigher flux with an LED generally requires higher current (and thereforehigher power). Most prior art devices, however, exhibit relatively highthermal resistance from their semiconductor radiation emitter to ambientand are compelled to limit power dissipation in order to avoid internaldamage. Thus, the best 5 mm T-13/4 THD packages are limited to about 110mW continuous power dissipation at 25° C. ambient temperature.

[0016] An additional problem faced by designers of conventional LEDdevices is that the wire bond used to join one of the LED leads to theLED chip can break or lose contact with the lead or the chip. Suchfailure can occur, for example, due to shear forces that are transferredto the wire bond through the encapsulant or thermalexpansion/contraction of the encapsulant around the wire bond.

[0017] The other forms of radiation emitters mentioned above alsoexperience performance degradation, damage, increased failureprobability or accelerated decay if exposed to excessive operatingtemperatures.

[0018] Consequently, it is desirable to provide a radiation emitterdevice that has a higher emission output than conventional LED deviceswhile being less susceptible to failure due to a break in the wire bondcontact or other defect that may be caused by excessive operatingtemperatures.

[0019] Similar heat dissipation problems exist with respect to otherelectronic components. For example, large heat sinks are often attachedto microprocessors of the type used in personal computers. Accordingly,an improved heat dissipation package for such electronic components isdesirable.

SUMMARY OF THE INVENTION

[0020] It is an aspect of the present invention to provide a relativelyhigh power and high power density radiation emitter device capable ofhigh radiant flux and/or luminous flux emission. It is a further aspectof the present invention to provide a radiation emitter deviceexhibiting relatively low temperature rise due to internal powerdissipation and increased reliability by virtue of relatively lowthermal resistance. To achieve these and other aspects and advantages inaccordance with one embodiment of the present invention, the radiationemitting device of the present invention comprises a sealed chamber; oneor more liquids or gels contained in the sealed chamber; anelectroluminescent emitter that emits optical radiation in response toan electrical signal, the electroluminescent emitter is disposed in thesealed chamber in physical and thermal contact with one of the liquidsor gels; and first and second electrical conductors electrically coupledto the electroluminescent emitter for energizing the electroluminescentemitter. A portion of the structure defining the sealed chamber may bepartially transparent to allow the radiation to enter or exit.

[0021] It is another aspect of the present invention to provide apackage for electronic components having improved heat dissipationcharacteristics. To achieve these and other aspects and advantages, theelectronic component package comprises first and second substratessealed together and spaced apart to define a sealed chamber, one or moreliquids or gels contained in the sealed chamber, and at least oneelectronic component disposed in the sealed chamber and thermal contactwith one of the liquids or gels. According to one embodiment, the atleast one electronic component includes a semi-conductor electroniccomponent. According to another embodiment of the invention, the firstsubstrate is a printed circuit board.

[0022] According to another embodiment, an optical radiation emittingdevice comprises: a sealed chamber; a fluid intermediary materialcontained in the sealed chamber and having a refractive index greaterthan 1.0; an electroluminescent emitter that emits optical radiation inresponse to an electrical signal, the electroluminescent emitterdisposed in the sealed chamber in physical and thermal contact with thefluid intermediary material; and first and second electrical conductorselectrically coupled to the electroluminescent emitter for energizingthe electroluminescent emitter.

[0023] According to another embodiment, an optical radiation emittingdevice comprises: a semiconductor radiation emitter that emits opticalradiation in response to an electrical signal; a protective barrier forprotecting the semiconductor radiation emitter, the protective barriercomprises a material that substantially maintains its in-band opticalproperties over time; and first and second electrical conductorselectrically coupled to the semiconductor radiation emitter forenergizing the semiconductor radiation emitter.

[0024] These and other features, advantages, and objects of the presentinvention will be further understood and appreciated by those skilled inthe art by reference to the following specification, claims, andappended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In the drawings:

[0026]FIG. 1 is a top elevational view of a radiation emitting deviceconstructed in accordance with a first embodiment of the presentinvention;

[0027]FIG. 2 is a perspective view of the radiation emitting device offirst embodiment of the present invention;

[0028]FIG. 3A is a cross-sectional view taken along line III-III of theradiation emitting device shown in FIG. 1;

[0029]FIG. 3B is a cross-sectional view of an alternative embodiment ofthe device shown in FIG. 1;

[0030]FIG. 3C is a cross-sectional view of an alternative embodiment ofthe device shown in FIG. 1;

[0031]FIG. 4 is a cross-sectional view of a radiation emitter deviceconstructed in accordance with a second embodiment of the presentinvention;

[0032]FIG. 5 is a cross-sectional view of a radiation emitter deviceconstructed in accordance with a third embodiment of the presentinvention;

[0033]FIG. 6A is a cross-sectional view of a radiation emitter deviceconstructed in accordance with a first variation of a fourth embodimentof the present invention;

[0034]FIG. 6B is a cross-sectional view of a radiation emitter deviceconstructed in accordance with a second variation of a fourth embodimentof the present invention;

[0035]FIG. 7 is a top view of a radiation emitter device constructed inaccordance with a fifth embodiment of the present invention;

[0036]FIG. 8 is a perspective view of a vehicle headlamp assemblyconstructed in accordance with the present invention;

[0037]FIG. 9 is a schematic diagram of an electrical circuit that may beprovided in one or more of the above embodiments;

[0038]FIG. 10 is a top view of an initial package subassembly inaccordance with a sixth embodiment of the present invention;

[0039]FIG. 11 is a top view of a finished package assembly constructedin accordance with the sixth embodiment of the present invention;

[0040]FIG. 12 is a graph illustrating the illuminance as a function ofpower for the package assembly shown in FIG. 11 with the chamber filledwith liquid and with the sealed chamber not filled with any liquid;

[0041]FIG. 13 is a graph of the relative spectral irradiance as afunction of wavelength obtained for the package assembly shown in FIG.11 with the chamber not filled with any liquid for various power levels;

[0042]FIG. 14 is a graph of the relative spectral irradiance as afunction of wavelength obtained for the package assembly shown in FIG.11 with the chamber filled with liquid for various power levels;

[0043]FIG. 15 is a cross-sectional view of an alternative embodiment ofthe device shown in FIG. 1;

[0044]FIG. 16 is a plan view of a subassembly of the device shown inFIG. 15;

[0045]FIG. 17A is a cross-sectional view of an alternative embodiment ofthe device shown in FIG. 1;

[0046]FIG. 17B is a cross-sectional view of an alternative embodiment ofthe device shown in FIG. 1; and

[0047]FIG. 18 is a cross-sectional view of an electronic componentpackage assembly constructed in accordance with an alternate embodimentof the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] Reference will now be made in detail to the present preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numeralswill be used throughout the drawings to refer to the same or like parts.

[0049] For purposes of description herein, the terms “upper,” “lower,”“right,” “left,” “rear,” “front,” “vertical,” “horizontal,” “top,”“bottom,” and derivatives thereof shall relate to the invention asviewed by a person looking directly at the radiation emitting sourcealong the principal optical axis of the source. However, it is to beunderstood that the invention may assume various alternativeorientations, except where expressly specified to the contrary. It isalso to be understood that the specific device illustrated in theattached drawings and described in the following specification is simplyan exemplary embodiment of the inventive concepts defined in theappended claims. Hence, specific dimensions, proportions, and otherphysical characteristics relating to the embodiment disclosed herein arenot to be considered as limiting, unless the claims expressly stateotherwise.

[0050] Several embodiments of the present invention generally relate toan improved optical radiation-emitting device useful in both high andlow power applications. Such embodiments of the present invention areparticularly well suited for use in limited power applications such asvehicles, portable lamps, and specialty lighting. By vehicles, we meanover-land vehicles, watercraft, aircraft and manned spacecraft,including but not limited to automobiles, trucks, vans, buses,recreational vehicles (RVs), bicycles, motorcycles and mopeds, motorizedcarts, electric cars, electric carts, electric bicycles, ships, boats,hovercraft, submarines, airplanes, helicopters, space stations,shuttlecraft and the like. By portable lamps, we mean camping lanterns,head or helmet-mounted lamps such as for mining, mountaineering, andspelunking, hand-held flashlights and the like. By specialty lighting wemean emergency lighting activated during power failures, fires or smokeaccumulations in buildings, microscope stage illuminators, billboardfront-lighting, backlighting for signs, etc. The light emitting assemblyof the present invention may be used as either an illuminator or anindicator. Examples of some of the applications in which the presentinvention may be utilized, are disclosed in commonly assigned PCTInternational Publication No. WO 00/55685 entitled “INDICATORS ANDILLUMINATORS USING A SEMICONDUCTOR RADIATION EMITTER PACKAGE,” by JohnK. Roberts et al.

[0051] Some of the embodiments of the present invention provide a highlyreliable, low-voltage, long-lived, light source for vehicles, portablelighting, and specialty lighting capable of producing white light withsufficient luminous intensity to illuminate subjects of interest wellenough to be seen and to have sufficient apparent color and contrast soas to be readily identifiable. Several of the radiation emitter devicesof the present invention may be well suited for use with AC or DC powersources, pulse-width modulated DC power sources, and electronic controlsystems. The radiation emitting devices of the present invention mayfurther be used to emit light of various colors and/or to emitnon-visible radiation such as IR and UV radiation.

[0052] As used herein, the term “radiation emitter” and “radiationemitting device” shall include any structure that generates and emitsoptical or non-optical radiation, while the term “optical radiationemitter” or “optical radiation emitting device” includes those radiationemitters that emit optical radiation, which includes visible light, nearinfrared (IR) radiation, and/or ultraviolet (UV) radiation. As notedabove, optical radiation emitters may include electroluminescent sourcesor other solid-state sources and/or photoluminescent or other sources.One form of electroluminescent source includes semiconductor opticalradiation emitters. For purposes of the present invention,“semiconductor optical radiation emitters” comprise any semiconductorcomponent or material that emits electromagnetic radiation having awavelength between 100 nm and 2000 nm by the physical mechanism ofelectroluminescence, upon passage of electrical current through thecomponent or material. The principle function of a semiconductor opticalradiation emitter within the present invention is the conversion ofconducted electrical power to radiated optical power. A semiconductoroptical radiation emitter may include a typical IR, visible or UV LEDchip or die well known in the art and used in a wide variety of priorart devices, or it may include any alternate form of semiconductoroptical radiation emitter as described below.

[0053] Alternate forms of semiconductor optical radiation emitters whichmay be used in the present invention are light emitting polymers (LEPs),polymer light emitting diodes (PLEDs), organic light emitting diodes(OLEDs) and the like. Such materials and optoelectronic structures madefrom them are electrically similar to traditional inorganic LEDs, butrely on organic compositions such as derivatives of the conductivepolymer polyaniline for electroluminescence. Such semiconductor opticalradiation emitters are relatively new, but may be obtained from sourcessuch as Cambridge Display Technology, Ltd. of Cambridge, and from Uniaxof Santa Barbara, Calif.

[0054] For brevity, the term semiconductor optical radiation emitter maybe substituted with the term LED or the alternate forms of emittersdescribed above or known in the art. Examples of emitters suitable forthe present invention include varieties of LED chips with associatedconductive pads for electrical attachment and that are emissiveprincipally at P—N or N—P junctions within doped inorganic compounds ofAlGaAs, AlInGaP, GaAs, GaP, InGaN, AlInGaN, GaN, SiC, ZnSe and the like.

[0055] LEDs are a preferred electroluminescent light source for use inthe radiation emitting devices of the present invention because LEDs donot suffer appreciable reliability or field-service life degradationwhen mechanically or electronically switched on and off for millions ofcycles. The luminous intensity and illuminance from LEDs closelyapproximates a linear response function with respect to appliedelectrical current over a broad range of conditions, making control oftheir intensity a relatively simple matter. Finally, recent generationsof AlInGaP, AlGaAs, InGaN, AlInGaN, and GaN LEDs draw less electricalpower per lumen or candela of visible light produced than incandescentlamps, resulting in more cost-effective, compact, and lightweightilluminator wiring harnesses, fuses, connectors, batteries, generators,alternators, switches, electronic controls, and optics. A number ofexamples have previously been mentioned and are incorporated within thescope of the present invention, although it should be recognized thatthe present invention has obvious other applications beyond the specificones mentioned which do not deviate appreciably from the teachingsherein and therefore are included in the scope of this invention.

[0056] Another preferred radiation source that may be used in theinventive light emitting assembly is a photoluminescent source.Photoluminescent sources produce visible light by partially absorbingvisible or invisible radiation and re-emitting visible radiation.Photoluminescent sources phosphorescent and fluorescent materials, whichinclude fluorescent dyes, pigments, crystals, substrates, coatings, aswell as phosphors. Such a fluorescent or phosphorescent material may beexcited by an LED or other radiation emitter and may be disposed withinor on the LED, or within or on a separate optical element, such as alens or diffuser that is not integral with an LED. Exemplary structuresusing a fluorescent or phosphorescent source are described furtherbelow.

[0057] As explained in more detail below, the present invention exhibitsa significantly lower thermal resistance than conventional LEDstructures by extracting heat from the LED chip(s) via all of thesurfaces of the LED chip(s) simultaneously instead of from primarilyonly one surface as in typical prior art LED devices. More specifically,the radiation emitter package of the present invention provides a sealedchamber or cavity containing a liquid or gel surrounding the LED chips,the liquid or gel having a moderate to high thermal conductivity, amoderate to high convectivity, or both. A material that is “moderate tohighly convective” is a material that is more effectively convectivethan either air or a conventional clear solid polymer such as epoxy orsilicone. “Effectively convective” means transporting substantialproportions of heat dissipated from a source by natural convection. TheLED chips may be mounted to a moderate to high thermal conductivityplate to which a transparent plate is sealed in spaced-apart relation todefine the sealed chamber or cavity. This combination is uniquelyeffective because heat is removed from large surfaces of the chip byconduction and by convective transport due to the natural convection ofthe liquid in the sealed chamber or cavity. Embodiments of the presentinvention are discussed below in connection with FIGS. 1-18. It will beappreciated that these embodiments are provided for purposes ofillustration only and are not limiting to the present invention.

[0058] FIGS. 1-3 show a radiation emitter device 10 constructed inaccordance with a first embodiment of the present invention. Device 10includes one or more radiation emitting sources 12, which are shown inFIG. 1 mounted to a first substrate 14. Although radiation emitters 12are preferably LED chips or dies, other forms of radiation emitters maybe used. The LED chips may be any conventional LED chip including thosewith vertical and lateral structure, transparent or absorbing substrate,electrically conductive or insulating substrate, tapered sides,Truncated Inverted Pyramid (TIP) construction, partial TIP construction,or flip chip, or other chip geometry, including LED chips utilizingAlGaAs, AlInGaP, GaAs, GaP, InGaN, AlInGaN, GaN, SiC, ZnSe and otherinorganic compound semiconductor materials. The anode can be on thetopmost surface of the chip, normally used for wirebond, and the cathodemay be on the bottom of the chip, normally connected with die attachadhesive, solder or eutectic bonding. As with some InGaN/SiC LED chips,this polarity may be reversed such that the cathode is at the topside,normally used for wirebond and the anode is at the bottom, normallyconnected with die attach adhesive, solder or eutectic bonding.Alternately, both anode and cathode may be topside of the chip as in alateral type InGaN/sapphire LED chip structure, normally connected bywirebonding. Both contacts may also be at the bottom side of the chip inflip-chip configuration, and normally attached with solder or die attachadhesive. LED chips suitable for use in the present invention includedare available from sources such as Cree, AXTI, UOE, LumiLEDS and UEC andothers. For purposes of this first embodiment, first substrate 14 may bemade of any electrically conductive material, and preferably a materialthat has relatively high thermal conductivity. Preferably, firstsubstrate 14 has a thickness of 0.5 to 6.1 mm and is made of copper oraluminum. As described below with respect to other embodiments, thefirst substrate may alternately be made of electrically nonconductivematerial (such as a ceramic, PC board, passivated metal clad board,etc.). The first substrate may also comprise all or a portion of orsurface of an external cooling structure such as a heat sink orthermoelectric cooler. An optional submount made of silicon, siliconcarbide, metal or other like materials, may be mounted between emitters12 and first substrate 14 to facilitate distribution of electrical poweror to moderate the physical properties of the emitters and the firstsubstrate.

[0059] Radiation emitter assembly 10 further includes a second substrate16 serving as a protective barrier that is spaced apart from firstsubstrate 14. At least a portion of second substrate 16 through whichradiation is emitted from radiation emitters 12 is substantiallytransparent to some or all of the wavelengths of radiation emitted fromemitters 12. Alternatively, all of second substrate 16 may betransparent to the radiation emitted from radiation emitters 12 oralternatively transparent to all visible, IR, and/or UV radiation. Forexample, second substrate 16 may be made of a 0.5 to 6.1 mm glass coverplate. For some embodiments, this glass may be conventional soda-limefloat glass, and in others it may be fused silica glass, borosilicatefloat glass or other glass composition. Second substrate may also bemade of tempered glass, an epoxy sheet, or transparent plastics that arealiphatic or olefinic in nature (e.g., polypropylene, polyethylene,dicylcopentadienes and polymethylpentenes). Such transparent aliphaticor olefinic plastics do not degrade when exposed to aprotic solventssuch as propylene carbonate, which is one possible liquid that may beused in the present invention. These transparent plastics also functionwell in solid-state systems that include pure solution-phase and partialsolution-phase electrolytes. These transparent plastics include: cyclicolefin copolymers such as TOPAS® available from Ticona, LLC of Summitt,N.J.; polymethylpentenes such as TPX™ manufactured by Mitsui;hydrogenated cyclo-olefin polymers such as ZEONEX® (based ondicyclopentadiene) manufactured by Nippon Zeon Company; and amorphouscycloolefin copolymers such as APEL™ manufactured by Mitsui. Anothersuitable polymer for the second substrate is polysulfone. Secondsubstrate 16 should maintain its “in-band” optical properties over anextended period of time. The term “in-band” optical properties shallmean those optical properties that affect or substantially influenceradiation at wavelengths emitted by the radiation emitters within theassembly. Specifically, it should maintain an absence of opticalabsorption (particularly, at the wavelength emitted by radiation sourceswithin the assembly), be resistant to hazing and scattering, and beresistant to reactions that cause it to turn yellow or other color overtime in such a manner as to unintentionally absorb significant portionsof radiation emitted by light sources within the assembly. In manyembodiments, second substrate 16 should be resistant to degradation uponprolonged, repeated or intense exposure to short-wavelength radiationsuch as blue, violet or UV light or upon exposure to ambient heat, heatfrom processing the assembly or from internal heat generated byoperating the assembly. For embodiments of the present inventioncontaining emitters of blue-green, blue, violet or UV light, it may beespecially important for the second substrate 16 to start and remainsubstantially transparent in the short wavelength bands emitted,avoiding the yellowing phenomena typical of some transparent polymermaterials, and thus avoiding excessive tendencies toward increasedabsorption of radiation produced by those emitters. Second substrate 16may also be treated with a coating (not shown), such as ananti-reflection coating, a barrier coating or other thin-film coating,on one or more of its surfaces. Such a coating may be employed, forexample to enhance extraction efficiency for optical radiation emittedby sources within the chamber 21 and exiting through surfaces of secondsubstrate 16. Another coating may be used to prevent permeation ofoxygen, water vapor or other agents through second substrate 16 into thechamber 21, to prevent impurities from leaching out of second substrate16 into liquid 20, or to prevent portions of liquid 20 from permeatinginto or reacting with second substrate 16.

[0060] Second substrate 16 is generally semi-rigid to rigid, however itmay be advantageous in some embodiments for second substrate 16 to bemade substantially flexible. By making second substrate 16 flexible, itmay be possible to accommodate bulk thermal expansion of liquid 20 asmay occur during prolonged operation of the assembly at high powerlevels, or during operation in environments having an ambienttemperature greater than that prevailing during the manufacture of theassembly. Such flexibility may be accomplished by utilizing thinnersheets of transparent material for construction of second substrate 16or by choosing more flexible materials to begin with. Alternately,second substrate 16 may be made flexible by increasing the area of thechamber 21 in such a way that portions of second substrate 16 aredisposed at considerable distance from retaining forces applied by seal18 (or by other mechanisms in the vicinity of seal 18).

[0061] As shown in FIGS. 1-3, assembly 10 further includes a seal (orgasket) 18 extending between first and second substrates 14 and 16 so asto define a closed region therebetween that is hereinafter referred toas a “sealed chamber.” As used herein, the term “chamber” may include acavity or similar structure. The seal or gasket 18 is preferably made ofepoxy, butyl rubber, a frit of metallic and/or glassy composition,ceramic, metal alloys such as solder, or other relatively inert barriermaterial. Within the sealed chamber is a liquid, gel, or other materialthat is either moderate to highly thermally conductive, moderate tohighly convective, or both. As used herein, a “gel” is a medium having asolid structure and a liquid permeating the solid structure. Because agel includes a liquid, the term liquid is used hereinafter to refer toliquids contained in gels as well as non-gelled liquids.

[0062] The liquid 20 is disposed within the sealed chamber 21 so as tosurround each of the LED chips 12 used in the device. Enough liquid 20may be disposed within the sealed chamber 21 such that the sealedchamber 21 is effectively filled. Alternately, the volume of liquid 20used may be less than the volume of the sealed chamber 21 such that aportion of the sealed chamber 21 remains occupied by a bubble of air,gas or vacuum (not shown). Such an unfilled portion of the chamber 21may be useful for accommodating thermal expansion of the liquid 20 or asa visual indication that the remainder of the chamber 21 is filled. Morethan one type of liquid 20 may also be used within the same sealedchamber 21 such that more than one zone is defined (not shown), andoccupied by a such liquids if they are not miscible. Such aconfiguration may be useful if different physical, optical or chemicalproperties are desired for the liquid 20 present in different portionsof the chamber 21. Liquid 20 is preferably, but not necessarily,electrically nonconductive. The materials utilized for substrates 14 and16, seal 18, and LED chips 12 preferably are selected such that they donot react or otherwise ionize the liquid 20 so as to cause the liquid tobecome significantly electrically conductive. High electricalconductivity of liquid 20 could create a short circuit across the LEDchips 12 depending upon how they are disposed in the sealed chamber 21.Preferably, liquid 20 has low to moderate thermal expansion, or athermal expansion that substantially matches that of first substrate 14,second substrates 16, or seal 18, and in some embodiments, a slightlyhigher thermal expansion may be desired to increase convection while inother embodiments, a low coefficient of thermal expansion may be desiredto minimize stress on the optional die attach (not shown), optionalsolder bumps (25) and seal 18. Liquid 20 is also preferably inert anddoes not readily decompose or otherwise react with external agents thatmanage to enter the sealed chamber 21 over time or with impuritiescontained within the sealed chamber 21 from the time of manufacture.Liquid 20 should also maintain its optical properties over time.Specifically, it should be resistant to reactions that cause the liquidto turn yellow or other color over time in such a manner as tounintentionally absorb significant portions of radiation emitted bylight sources within the assembly. For applications where the assemblywill be exposed to short wavelength radiation such as UV, violet, blueor blue-green optical radiation from the ambient environment or fromemitters within the assembly, liquid 20 should be resistant todegradation upon prolonged, repeated or intense exposure such radiation.For embodiments of the present invention containing emitters ofblue-green, blue, violet or UV light, it may be especially important forthe liquid 20 to remain substantially colorless, avoiding excessivetendencies toward increased absorption of radiation produced by thoseemitters. Liquid 20 should also be compatible with the seal material.The liquid should also be substantially transparent to some or all ofthe wavelengths of radiation emitted from the radiation emitters 12. Itwill be appreciated however, that liquids may be selected or dyes may beutilized to selectively filter the radiation emitted from the radiationemitters 12. Liquid 20 also preferably has an index of refractionbetween that of the radiation emitters 12 and the glass or otherwisehave an index that approximately matches one of the emitters or theglass. Another benefit that may result from providing liquid 20 incontact with emitters 12 and any optional wire bond, is that the liquidprovides viscous damping of any vibration of the wire bond.Additionally, liquid 20 (also referred to herein as an intermediarymaterial that is disposed between the emitter(s) and the secondsubstrate or protective barrier) may provide increased opticalextraction efficiency by minimizing internal reflection within thedevice. In this respect, it should be noted that most LED chip materialspossess high refractive indices, such that greater light extractionlosses occur by total internal reflection and internal absorption whensuch chips are surrounded by media with very low refractive indices. Airor other atmospheric gasses typically have a refractive index near 1.0such that a configuration involving juxtaposition of LED chips directlyagainst air leads to poor optical coupling. For this reason, liquid 20is selected to have a relatively higher refractive index, consistentwith other functional requirements. The refractive index of liquid 20 atthe emission wavelength of sources within the assembly is generallyhigher than about 1.3, but is more preferably higher than 1.4 and insome cases may be higher than 1.5. With addition of small-particlefillers or other additives, liquid 20 may become a suspension orsolution with an effective refractive index as high as 2.5. Suchadditives may include inorganic fillers or organic materials, includingnanoparticles, doped nanocrystals, conventional phosphors. Certain typesof optical fluids such as oils may also be available with or withoutsuch fillers or additives and having elevated refractive indices greaterthan 1.4 and as high as 3.0. Liquid 20 may be propylene carbonate oranother liquid or gel having one or more of the above describedproperties. One commercially available liquid that may be used isGalden® D02TS available from Montedison S.P.A. of Milan, Italy.

[0063] The liquid 20 may be dispensed within the sealed chamber 21 byvacuum back-filling or other conventional techniques such as those usedto dispense an electrochromic solution between two glass substrates whenmaking an electrochromic mirror or window. One or more fill holes may beprovided in either the seal or in one or both of the substrates. Afterthe sealed chamber 21 is filled with liquid 20, the hole(s) may beplugged with a UV-curable or other plug material.

[0064] In the embodiment shown in FIGS. 1-3, the substrates areapproximately one inch by one and one quarter inch rectangles. The sizeof the substrates may, however, be much bigger and be as large as anarchitectural window or the like, or may be smaller depending on theapplication. Preferably, the volume of liquid in the sealed chamber 21defined by the seal and the two substrates is more than about 20 timesgreater than the volume of the radiation emitters to ensure sufficientheat transport. In some embodiments, it may be possible to reduce thisvolume as low as 2 times the volume of the radiation emitters. Althoughsubstrates 14 and 16 are depicted in FIGS. 1 and 2 as being rectangular,it will be appreciated that the substrates may have virtually any shape.Square, circular, hexagonal and octagonal shapes may be desirable inspecific applications. Seal 18 need not be formed in the same shape asthat of the substrates. Seal 18 serves to bond the two substratestogether and form sides of the sealed chamber 21 in which liquid 20 iscontained. Seal 18 should also serve as an environmental barrier so asto impede diffusion of water, oxygen, and other substances into thesealed chamber 21 while also impeding liquid 20 from exiting the sealedchamber 21. Seal 18 may also function as a spacer for maintaining theseparation distance of substrates 14 and 16. Spacers (not shown) in theform of pillars, glass beads, etc. disposed between the substrates maybe used as the sole means for maintaining the separation distance ofsubstrates 14 and 16 or as a supplement to the spacing function servedby the seal. The radiation emitters or other electrical components inthe sealed chamber 21 (described further below) may also provide thisspacing function.

[0065] To enable electrical current to flow to and through anyelectroluminescent radiation emitters 12 that may be present in thesealed chamber 21, electrical conductors are provided that areelectrically coupled to emitters 12 and extend out from the sealedchamber 21. When an electrically conductive first substrate 14 isutilized, the negative or positive terminal of the emitters 12 may bedirectly mounted to first substrate 14 while the other of the terminalof emitters 12 may be soldered (note solder bumps 25) or otherwiseelectrically connected to a conductor 22 provided on the bottom innersurface of second substrate 16. Conductor 22 may be made of metal ormade of indium tin oxide (ITO), which is a common transparent conductor.With such a configuration, the spacing between first substrate 14 andsecond substrate 16 would be approximately equal to the thickness ofemitters 12, which is typically on the order of 0.012 inch, but may beas low as 0.001 inch or as high as 0.500 inch. In this embodiment,partial conductivity of liquid 20 may supplement or serve as thereplacement for solder bumps 25 at the top of the emitters 12 makingelectrical connection to conductor(s) 22 on second substrate 16.

[0066] As shown in FIG. 2, electrical leads 26 and 30 may be coupled toelectrical conductor 22 and first substrate 14 by respective conductiveclips 24 and 28. Such clips may have a construction similar to thoseutilized in electrochromic devices. An example of suitable clips isdisclosed in U.S. Pat. No. 6,064,509 entitled “CLIP FOR USE WITHTRANSPARENT CONDUCTIVE ELECTRODES IN ELECTROCHROMIC DEVICES” filed onAug. 22, 1997, by William L. Tonar et al. Additionally, two pairs oflead posts 31 may extend from opposite ends of clips 24 and 28 so as tofunction as leads 26 and 30. Such lead posts would allow the package tobe mounted to through-holes in a printed circuit board.

[0067] While first substrate 14 is shown as a flat plate, it will beappreciated by those skilled in the art that substrate 14 may includerecesses, protrusions, fins, etc. to increase the exterior surface areaand maximize its effectiveness as a heat sink. For example, a heat sinksuch as that currently employed on Pentium or Athlon® CPU chips may beused. Additionally or alternatively, a fan, forced convection system, orPeltier type cooling system may be used to increase the dissipation ofheat from the assembly. For example, a Peltier type cooling structuremay be used optionally comprising a Peltier cooler 33, heat sink 35,and/or fan 37 attached to the backside of first substrate 14, as shownin FIG. 3B, or otherwise made integral with first substrate 14. Otherthermoelectric cooling materials, structures or means may also besubstituted for the Peltier cooling structure in this configuration. Asdescribed further below, at least one electrical component 31 may beprovided in the sealed chamber 21 along with emitter(s) 12.

[0068] Furthermore, substrate 14 may include cup-shaped recesses on itsupper surface with one such recess for each radiation emitter 12provided in the device. Provided substrate 14 has a reflective uppersurface, such recessed cups would serve to redirect light emitted fromthe sides of the emitters in a forward direction through secondsubstrate 16. Alternatively, if substrate 14 is not otherwisereflective, the top surface may be coated with a reflective materialparticularly within such recessed cups or a reflective pad may belocated under the emitters. Such a reflective pad may be the electricalconductor, when a nonconductive first substrate is employed.

[0069] Similarly, second substrate 16 need not have a flat upper orlower surface. Substrate 16 may include integral microlenses, diffusers,or the like. Additionally, graphic masks, appliques, or color filtersmay be applied to, or made integral with, one or more of the surfaces ofsecond substrate 16. For example, an applique may be applied that allowslight emitted from the emitters to be transmitted through letters of asign, such as an exit sign. In this manner a high brightness, back-litdisplay panel may be provided. The panel may be static (e.g., facia,applique, screen-printed mask, etc.) or dynamic (e.g., a liquid crystaldisplay (LCD) panel). When an LCD panel is used as second substrate 16,or otherwise attached to or mounted proximate substrate 16, it ispreferred, but not essential, that the radiation emitting device includered, green, and blue (RGB) LEDs or alternatively binary complementarywhite emission source combination or an InGaN LED/fluorescent whiteemitting source combination, to enable a dynamic full-color display.

[0070] As illustrated in the drawing figures, the radiation emittingassembly may include one or more emitters 12. Radiation emitters 12 mayemit light within the same wavelength bands or may emit light indifferent wavelength bands. For example, one or more LEDs may emit IR orUV radiation, while the others emit visible radiation. As anotherexample, the radiation emitters may emit light of complementary colorssuch that the light emitted from radiation emitters 12 overlaps andforms white light or light of a color that is not otherwise emitted fromany of the radiation emitters individually. To produce white light oralmost any other color of illumination, three radiation emitters may beused with one emitting red light, another emitting blue light, and thethird emitting green light. Alternatively, two radiation emitters may beused that emit binary complementary colors to produce effective whitelight in the manner disclosed in commonly assigned U.S. Pat. No.5,803,579, entitled “ILLUMINATOR ASSEMBLY INCORPORATING LIGHT EMITTINGDIODES,” by Robert R. Turnbull et al.

[0071] When more than one radiation emitters 12 that areelectroluminescent are utilized in the inventive device, separateconductive leads may be provided to each electroluminescent emitter 12so that the emitters may be independently activated and theirintensities independently controlled. For example, rather than utilizinga single transparent conductive layer 22 across the entire surface ofsecond substrate 16 in the embodiment shown in FIGS. 1-3, thetransparent conductive layer 22 may be etched or otherwise patterned soas to provide discrete connections to the top, normally positive,terminals of emitters 12. Such an example is shown in FIG. 3C where theconductive layer is patterned to form two discrete connections 22 a and22 b. In this case, two separate and smaller clips (not shown) may beused in place of clip 24 (FIG. 2). Conversely, if first substrate 14 ismade of an electrically nonconductive material, as in the embodimentsdescribed below and shown in FIGS. 4, 5, 6A, 6B, 10, 11, and 18 separateelectrically conductive traces may be formed on the first substrate toprovide discrete connections to the positive and/or negative terminalsof emitters 12.

[0072] In the event it is desired to have the inventive radiation deviceemit white light or other colored light with a hue differing from thatof light emitted by enclosed electroluminescent emitters 12, it may bedesirable to incorporate a photoluminescent radiation source such as aphosphorescent or fluorescent material into substrate 16 or in a layeron substrate 16. Alternatively, a photoluminescent source may be appliedas one or more blobs over an electroluminescent emitter 12, or may bedissolved or suspended in liquid 20. Photoluminescent sources could beused to enable the assembly to emit substantially white light when thephotoluminescent source is irradiated by the radiation emitted fromelectroluminescent emitters 12. Photoluminescent sources could also beused to generate green, blue-green, amber, orange, or red light whenirradiated by UV, violet, or blue emitting electroluminescent emitters12. An example of the use of photoluminescent sources in this manner isdisclosed in commonly assigned U.S. patent application Ser. No.09/723,675, entitled “LIGHT EMIT G ASSEMBLY,” and filed on Nov. 28, 2000by John K. Roberts et al.

[0073] A photoluminescent source may additionally or alternatively bedispersed, dissolved, or suspended in liquid 20. The convection ofliquid 20 may tend to keep the photoluminescent material in suspensionor in solution. Such dispersal of photoluminescent media within theliquid 20 may also help maintain uniformity of color and/or luminance ofthe device and may help limit degradation of the photoluminescent mediawith long term use.

[0074] While liquid 20 has been described above as preferably beingelectrically nonconductive, liquid 20 may nevertheless be conductiveprovided that the resistance of liquid 20 is greater than that betweenthe negative and positive terminals of the radiation emitters 12 in thechamber 21 and that the resistive path through the liquid between theelectrical conductors is much greater than the resistive path throughthe liquid between each electrical conductors and the negative orpositive terminals to which they are respectively coupled. Conceivably,by using a conductive liquid, the need for a wire bond or solder may beeliminated by allowing current to flow to an electroluminescent emitter12 from first substrate 14 or second substrate 16 via a thin portion ofliquid 20.

[0075] Additionally, additives such as anti-oxidants or UV stabilizersmay be added to liquid 20 to improve system life. Electrolytes can becarefully added in small quantities to establish any optional electricalconductivity desired.

[0076]FIG. 4 shows a radiation emitting device 40 constructed inaccordance with a second embodiment of the present invention. As shown,radiation emitting device 40 includes an electrically nonconductivefirst substrate 32, a second substrate 16, and a seal 18 disposedbetween the two substrates to define a sealed chamber 21 in which aliquid or gel 20 is contained. Device 40 further includes a firstelectrical trace 34 and a second electrical trace 36 provided on theupper surface of first substrate 32. As shown in FIG. 4, two radiationemitters 12 are mounted on first electrical trace 34 with their cathodesin electrical contact with trace 34. Trace 34 extends outward from thesealed chamber 21 so as to enable electrical contact with an externaldevice. Second trace 36 also extends from within the sealed chamber andis electrically coupled to wire bonds 38 that are coupled to thenegative or positive terminals of radiation emitters 12. As suggestedabove, both radiation emitters 12 may share common electrical traces ormay have discrete traces for allowing for independent activation andcontrol.

[0077] First substrate 32 may be made of alumina or other ceramicsubstrate, such as beryllia ceramic, passivated metals, metal clad ormetal core printed circuit board, passivated, anodized, or laminatedmetal printed circuit board, or may be made of glass, an epoxy sheet, oran aliphatic or olefinic plastic such as those discussed above. If boththe first and second substrates are made of plastic, it may be possibleto configure and join the two substrates without requiring a seal orother spacers. Commonly-assigned U.S. Pat. No. 6,193,379, entitled“ELECTROCHROMIC ASSEMBLY INCLUDING AT LEAST ONE POLYMERIC SUBSTRATE,”filed on Jun. 9, 2000, discloses various plastic materials andstructures for forming sealed chambers when used for containing anelectrochromic medium. Such disclosed structures may be used in thelight emitting assembly of the present invention.

[0078] Device 40 may further include a micro-groove lens 41, which maybe a Fresnel lens, a diffraction grating, total internal reflection(TIR) lens, catadioptric lens, kinoform lens, a holographic opticalelement (HOE), or other optical lens. Lens 41 may be integrally formedon either the inside or outside surface of second substrate 16 or may beoptically coupled to second substrate 16. A suitable micro-groove lensis disclosed in commonly assigned U.S Provisional Patent Application No.60/270,054 entitled “RADIATION EMITTER DEVICE HAVING A MICRO-GROOVELENS,” filed on Feb. 19, 2001 by John K. Roberts.

[0079]FIG. 5 shows a radiation emitting device 50 constructed inaccordance with a third embodiment of the present invention. Like device40 of the second embodiment, device 50 utilizes an electricallynonconductive first substrate 32 that is spaced apart from a secondsubstrate 16 by a seal 18 that forms a sealed chamber 21 in which aliquid or gel 20 is contained. Device 50 differs from device 40 in thata lateral-type LED 52 with two top-side electrode contacts is utilized.LED 52 may be directly mounted on substrate 32 within a gap formedbetween a first electrical trace 54 and a second electrical trace 56that are provided on the upper surface of substrate 32. As in the secondembodiment, electrical traces 54 and 56 extend from within the sealedchamber 21 to the exterior of the device to allow for an electricalsignal to be applied to LED chip 52 from the exterior of device 50.First trace 54 is provided to be coupled to a first wire bond 58 that iscoupled to the anode of LED chip 52. Second trace 56 is provided forcoupling to a second wire bond 60 that is coupled to the cathode of LEDchip 52.

[0080] Both the embodiments shown in FIGS. 4 and 5 utilize electricaltrace wires that are bonded to one of the contact terminals of theradiation emitters. Preferably, the trace wires are flat ribbon wireshaving a rectangular cross-section and are bonded to the contactterminal of the radiation emitter using a wedge bond. Such a wire andbond reduce the spacing needed to accommodate the radiation emittersbetween the substrates since they provide a lower profile bond than aconventional wire having a circular cross-section that is bonded using aball-shaped bond. However, in some embodiments, conventional circularbond wire may be used, and in other embodiments, none may be necessary.

[0081]FIGS. 6A and 6B show two variations of a fourth embodiment of thepresent invention whereby irregularly shaped substrates are used to formthe sealed chamber 21. Specifically, in FIG. 6A, a structure is shown inwhich the back and at least part of the sides of the sealed chamber 21are defined by an irregularly-shaped substrate 70, which may betransparent, partially transparent or opaque, and may be made of metalor plastic. Substrate 70 includes an opening 71 that lies aboveradiation emitter(s) 12. As illustrated, a window substrate 72 that issubstantially transparent to the radiation emitted from radiationemitters 12, is secured to substrate 70 across opening 71. A seal orgasket 74 may be disposed between window substrate 72 andirregularly-shaped substrate 70 to seal the chamber 21.

[0082] In FIG. 6B, a structure is shown in which an irregularly shapedtransparent second substrate 75 is provided to define the front and atleast a portion of the sides of the sealed chamber 21. Second substrate75 may be ultrasonically welded or otherwise bonded to first substrate32 in order to seal the chamber 21. As illustrated, second substrate hasa dome-like shape and includes a peripheral shoulder 76 and rim 77 forengaging the edges of first substrate 32. Electrical connections toradiation emitter(s) 12 may extend through vias formed in firstsubstrate 32 that extend from an inner surface to an outer surfacethereof. The chamber 21 may be filled with the second substrate invertedand prior to ultrasonic welding. Alternatively, a fill hole may beprovided through first substrate so that the chamber may be filled afterwelding. A UV curable or other plug may then be used to seal the fillhole.

[0083]FIG. 7 shows a fifth embodiment of the present invention. In thisfifth embodiment, a reflective mask 80 is provided on a surface ofsecond substrate 16. The reflective mask 80 includes a plurality ofnon-masked openings 82 above each radiation emitter 12. Mask 80 mayoptionally include a small reflective spot 84 directly over each emitter12 so as to prevent light from directly emitting from an emitter 12through mask 80. In this manner, emitters that emit light of differentcolors may be disposed within the chamber 21, and the light emitted fromthe emitters will mix within the chamber 21 prior to being emitted fromthe assembly. Mask 80 may be a patterned reflective or diffuse coatingor a filter and be made integral with patterned conductors if used.Patterns other than those shown may be used to optimize various opticalqualities without departing from the scope of the invention.

[0084]FIGS. 15 and 16 show yet another embodiment of the presentinvention. As shown in the cross sectional view of FIG. 15, radiationemitted from emitters 12 is either nearly completely transmitted,partially transmitted and partially internally reflected, or nearlycompletely internally reflected from second substrate 16 depending uponthe angle at which the radiation strikes the surfaces of secondsubstrate 16. Whether radiation (i.e., a light ray) is internallyreflected depends upon whether the light ray strikes the surface at anangle that is greater than the critical angle as determined byapplication of Fresnel's equations and Snell's Laws. If the entire uppersurface of first substrate 14 served as a specular reflector, thoselight rays T that are totally internally reflected from a surface ofsecond substrate 16 would continue to be totally internally reflectedfrom the upper surface of first substrate 14 and then again from thesurfaces of second substrate 16. To cause the light rays T that wouldotherwise be totally internally reflected, to ultimately exit throughthe second substrate of the radiation emitting device, upper surface offirst substrate 14 may have different reflective zones—namely, aspecularly reflective zone 301 and a diffuse reflective zone 303. Asshown in FIGS. 15 and 16, separate specularly reflective zones 301 areprovided for each emitter 12 and are circular in shape with theassociated emitter 12 disposed in the center of the circle. Theremainder of the upper surface of first substrate 14 (with the exceptionof that area covered by electrical traces and contact terminals)constitutes the diffuse reflective zone 303. Specular reflective zones301 may be provided as a portion of the patterned electrical conductortraces 304. As will be apparent to those skilled in the art, thediameter of the circular specular reflection zone 301 is selected to besmall enough not to reflect light rays that are totally internallyreflected from a surface of the second substrate 16, and yet largeenough to reflect all other light. The diffuse reflective zone 303 isprovided to diffuse those light rays T that are totally internallyreflected from a surface of the second substrate 16 and thereby reflectthe light at angles that are likely to allow the light to exit thesecond substrate 16. Diffusely reflective zone 303 may have a coatingincluding a photoluminescent material.

[0085] While specular reflection zones 301 are shown as being circularon a planar surface, it will be appreciated that the first substrate 14may include recessed reflective cups. FIGS. 17A and 17B show alternatevariations of such a construction. Specifically, FIG. 17A shows the useof reflective partitions 311 between radiation emitters 12 so as todivert those light rays that would otherwise strike a surface of secondsubstrate 16 at an angle exceeding the critical angle. Reflectivepartitions may form a parabolic reflective cup or other shaped cup andmay be specular or diffuse in surface character. FIG. 17B shows avariation of the structure shown in FIG. 17A in which reflectivepartitions 313 are integrally formed in the upper surface of firstsubstrate 315. Note that partitions 311 and 313 in the above embodimentsmay function as a spacer between the first and second substrates.

[0086]FIG. 8 shows a vehicle headlamp 2600 constructed in accordancewith the present invention. As shown, the headlamp includes a lightemitting assembly similar to those shown above, except that it includesan array of radiation emitters 2603 and 2605 within the sealed chamber21 that is formed between a first substrate 2601, a second substrate2630, and a seal (not shown). Second substrate 2630 preferably includesa plurality of micro-lenses 2631 formed in its outer surface above eachone or each group of emitters 2603, 2605. First substrate 2601preferably includes a heat extraction member 2621 and a plurality ofreflective cups 2602 and 2605 in which each one or each group ofemitters are mounted. Emitters 2603 are connected to electricalconductor strip 2607 through a wire bond 2609 and a resistor 2611.Emitters 2605 are connected to electrical conductor strip 2613 through abonding wire 2615 and a resistor 2617. A second assembly similar to thatshown in FIG. 8 may also be disposed in a common headlamp housing andpreferably disposed at an angle relative to the first assembly so as toproduce high beams. By utilizing the high power light emitting assemblyof the present invention, vehicle headlamps may be constructed thatrequire fewer LEDs or other emitters to produce the requisiteillumination levels that are expected for vehicles. Headlamp 2600 mayalso be a fog lamp or other lamp assembly.

[0087]FIG. 9 shows an examplary circuit 100 that may be used in theabove embodiments of the present invention. As shown, three externalconnections are provided including a ground contact 102, a first supplyvoltage contact 104, and a second supply voltage contact 106. Secondsupply voltage contact is provided to enable a bias voltage to beapplied between a first LED 110, and two second LEDs 112 via a resistor114, and thereby adjust the relative intensity of the second LEDsrelative to the first LED, which is particularly advantageous when thefirst and second LEDs emit light of different colors. A resistor 118 iscoupled between the first LED and first supply voltage contact. Resistor118, first LED 110, and second LEDs 112 are coupled in series betweenfirst supply voltage contact 104 and ground contact 102. As shown inFIG. 9, a plurality of such series-connected LEDs may be connected inparallel. Portions of circuit 100 may be printed on one or both ofsubstrates 14 and 16. Portions of circuit 100 may be disposed inside oroutside of the sealed chamber 21, with contacts 102, 104, and 106extending out of the chamber for external connection. Resistors 114 and118 may likewise be provided outside of the chamber to lower the heatgenerated inside the chamber.

[0088] In a preferred embodiment, LEDs 110 emit blue-green light whileLEDs 112 emit amber light. With such an arrangement, effective whitelight may be emitted from the assembly.

[0089]FIG. 10 shows an initial subassembly that forms a part of thefinal assembly shown in FIG. 11 in accordance with a sixth embodiment ofthe present invention. The package 150 includes a printed circuit board155, which in the example provided below, is made of BeO. Variouselectrically conductive traces are formed on circuit board 155.

[0090] In the example shown in FIGS. 10 and 11, a first trace 160extends from a first electrical contact 162 to a first terminal of eachof four first resistors 164 a-164 d. Traces 166 a-166 b extend from asecond terminal of respective resistors 164 a-164 d to a respectiveanode of a corresponding pad 168 a-168 d upon which is mounted a firstset of LEDs 170 a-170 d. First LEDs 170 a-170 d are mounted with theiranode in electrical contact with pads 168 a-168 d, respectively. Traces166 a-166 d also extend to a position proximate pads 172 a-172 d uponwhich are mounted respective second LEDs 174 a-174 d. Second LEDs aremounted with their anodes in electrical contact with pads 172 a-172 d.Wire bonds 176 a-176 d electrically couple the cathodes of second LEDs174 a-174 d to the end of trace 166.

[0091] The cathodes of first LEDs 170 a-170 d are electrically coupledvia corresponding wire bonds 178 a-178 d to a respective trace 180 a-180d, which in turn are coupled to respective first terminals of secondresistors 182 a-182 d. Second terminals of resistors 182 a-182 d, inturn, are commonly coupled to a trace 184, which extends and iselectrically coupled to a second contact terminal 186. The resistors 164a-164 d and 182 a-182 d are preferably 2 Ω, 1 W thick film resistorsthat are printed on circuit board 155.

[0092] Pads 172 a-172 b, to which the anodes of second LEDs 174 a-174 dare respectively coupled, are electrically coupled to respective traces188 a-188 d. Each of these traces 188 a-188 d is connected by means of arespective wire bond 190 a-190 d to another respective trace 192 a-192 don the opposite side of trace 184. Traces 192 a-192 d are respectivelycoupled to cathodes of respective third LEDs 194 a-194 d by a wire bond196 a-196 d. The anodes of third LEDs 194 a-194 d are mounted oncorresponding pads 198 a-198 d, which in turn are commonly coupledtogether via a trace 200 that extends and is electrically coupled to athird contact terminal 202.

[0093] With the circuit layout as shown in FIG. 10, the resultingcircuit has a schematic corresponding generally to FIG. 9, where firstLEDs 170 a-170 d correspond to LEDs 110, second and third LEDs 174 a-174d and 194 a-194 d correspond to LEDs 112, first resistors 164 a-164 dcorrespond to resistors 114, and second resistors 182 a-182 d correspondto resistors 118.

[0094] In a preferred embodiment and in the example discussed below,first LEDs 170 a-170 d are preferably InGaN LED chips that emitblue-green light. Both the second and third LEDs 174 a-174 d and 194a-194 d are AlInGaP LED chips that emit amber light. By utilizing theseLED chips, effective white light may be emitted from the package inaccordance with the teachings of U.S. Pat. No. 5,803,579 entitled“ILLUMINATOR ASSEMBLY INCORPORATING LIGHT EMITTING DIODES” by Robert R.Turnbull et al.

[0095] Once the above-described circuit has been constructed, a coverglass 205 is attached to circuit board 155 with an epoxy seal 210, whichencircles the circuit components, with the exception of electricalcontacts 162, 186, and 202 and with the exception of a small holethrough which the resultant sealed chamber 21 may be filled with aliquid or gel. In the example discussed below, the seal chamber wasfiled with Galden® D02TS. Subsequently, the hole provided in the epoxybetween cover 205 and circuit board 155 was plugged with a plug 212 madeof Dynax UV cure adhesive. The resultant structure is shown in FIG. 11.

[0096] As apparent from FIG. 11, the resultant final package assemblyincludes three contact pads 162, 186, and 202, which extend outward fromthe sealed chamber 21 and up to the edge of printed circuit board 155.In this manner, a conventional low insertion force edge connector may beconnected to the contact pads for coupling to the drive circuit. Such anedge connector may be a conventional PCI or ISA slot connector. Itshould be understood that another number of contact pads may be used,dependent on the electrical configuration used.

[0097] The invention will be further clarified by the following example,which is intended to be exemplary of the invention and are not intendedin any manner to limit the invention.

EXAMPLE

[0098] To demonstrate the effectiveness of the present invention, apackage assembly was constructed as illustrated in FIGS. 10 and 11 anddescribed above. The structure had a length of approximately 1.5 inchesand a width of approximately 1.5 inches, with the external contact padsbeing approximately 0.25 inch long. To demonstrate the effectiveness ofthe present invention, the illumination from the device was measured atvarious power levels prior to filling the sealed chamber 21 with anyliquid. Then, the assembly was filled with liquid and plugged and theilluminance was again measured at the same power levels. The results ofthese measurements are illustrated in FIG. 12, with the illuminancemeasured in foot-candles at 18 inches. As apparent from FIG. 12, theprovision of the liquid in physical and thermal contact with the LEDsimproved their performance markedly. The improvement increased as theapplied power increased. It should be understood that, for this sample,increased illuminance at each indicated power level for the filledradiation emitter relative to the unfilled radiation emitter is anindication of reduced junction operating temperature and reducedassembly thermal resistance.

[0099]FIG. 13 is a plot of the relative spectral irradiance as afunction of wavelength with the chamber 21 of the device not filled withany liquid. The relative spectral irradiance was measured at fivedifferent power levels. Subsequently, after the device was filled withliquid, the same plots were obtained and are illustrated in FIG. 14.

[0100] While the above invention has been described with respect to theprovision of optical radiation emitters and other radiation emittingdevices within a sealed chamber 21 of the inventive package, theinventive package may similarly be used to improve the heat dissipationfrom other electronic components. For example, as shown in FIG. 18, amicroprocessor 230, a sensor 240, a resistor 245, and other electroniccomponents, particularly other semiconductor electronic components, maybe disposed within sealed chamber 250 that is formed between two members255 and 260. Examples of other electronic components that coulddesirably be placed in the sealed chamber either alone or in combinationwith radiation emitters, microprocessors, resistors, sensors or othercomponents, including thermistors, diodes, Zener diodes, photodiodes,transistors, voltage regulators, Peltier effect diodes or otherthermoelectric cooling chips or materials, phototransistors, etc.Members 255 and 260 may have any of the constructions discussed above.However, if none of the components within the sealed chamber are opticalcomponents, both members 255 and 260 may be opaque. Without such aconstraint, first member 255 may, for example, be a printed circuitboard while second member 260 may be a heat sink, preferably made of ahighly thermally conductive material and having a large surface area.Such a large surface area may be provided by including various fins 262extending outward away from the sealed chamber. As also shown in FIG.18, various passageways 264 may be provided through heat sink member 260through which liquid may flow. These passages may join into sealedchamber 250 to allow the liquid contained therein to flow through thepassageways to expedite heat dissipation from the liquid.

[0101] The electronic components mounted in the chamber may be surfacemount (SMT), through-hole (THD), ball grid array (BGA), chip-on-board,chip-on-glass, or other common semiconductor device form. Electricalconnections to/from/between these components, and any patternedconductors within the chamber or to contacts exiting the chamber, may besolder, solder bump, solder paste, conductive epoxy, eutectic attach,wire bond, leadframe, or other electrical connection means.

[0102] Another alternative embodiment would enable both members 255 and260 to be printed circuit boards that are sandwiched together by anepoxy seal and filled with a liquid or gel. This may enable heatdissipation in accordance with the present invention from circuitcomponents mounted to either or both of the circuit boards.

[0103] It should also be appreciated that the components shown in FIG.18 may be combined with a radiation emitter as in the other embodimentswithin a single sealed chamber. It may, for example, be beneficial toinclude resistors and/or a sensor within the same sealed chamber as theradiation emitters. Such a sensor may be a thermal sensor, such as athermistor, so as to provide a mechanism for monitoring the temperatureof the liquid within the sealed chamber and for enabling the currentprovided to the LED chips to be controlled as a function of thetemperature within the chamber. This would allow the LED chips to bedriven at their maximum safe level. It may also be desirable to includea voltage regulator to regulate the electrical drive signal to anyelectroluminescent radiation sources in the chamber. Additionally, itmay be desirable to include any one or combination of transistors,phototransistors, diodes, photodiodes, or Zener diodes in the sealedchamber.

[0104] It may further be desirable to dispose an optical sensor withinthe same sealed chamber as the radiation emitters. Commonly assignedU.S. Provisional Application No. 60/192,484, entitled “LAMP ASSEMBLYINCORPORATING OPTICAL FEEDBACK,” and filed on Mar. 27, 2000, by JosephS. Stam et al. and U.S. patent application Ser. No. 09/818,958 entitled“LAMP ASSEMBLY INCORPORATING OPTICAL FEEDBACK,” filed on Mar. 27, 2001by Joseph S. Stam et al. disclose the advantages of utilizing an opticalsensor in combination with a plurality of LED chips. Such sensors may beemployed for many purposes such as to provide feedback for the controlof electroluminescent emitters 12 in the device. In the event an opticalsensor is provided in the sealed chamber, it may be desirable toincorporate light absorbing materials within the sealed chamber so as toeffectively filter the light that reaches the sensor.

[0105] The radiation emitter device described herein can be used toprovide a near IR night vision system for use in automobiles and otherapplications. A radiation emitter device is constructed as describedabove using IR LED die emitting radiation at a wavelength longer thanthe human eye can detect but still within the sensing capability of anelectronic image sensor. Preferably, this wavelength range is between800 and 880 nm, but may be as low as 700 nm or as high as 1200 nm. SuchIR-emitting LED die are available from Tyntec Corporation of Hsinchu,Taiwan.

[0106] Current vehicular night vision systems have several disadvantageswhich are overcome by using a near IR night vision system. Currentsystems sense far IR radiation—essentially heat. Detectors which sensefar IR radiation are significantly more expensive than detectors whichsense near IR radiation. Additionally, glass is opaque to far IRradiation thus mandating that the sensor be placed outside of thevehicle's cabin thereby subjecting the system to much harsherenvironmental conditions. Also, glass optics cannot be used and moreexpensive optical materials transparent to far IR radiation must be usedinstead. Finally, objects which are not at a higher temperature than theambient surroundings are not sensed as well as hot objects. Therefore,it is possible to have an object in the road which is not adequatelydetected by a far IR system.

[0107] The radiation emitter device of the current invention may thus beconfigured to emit radiation illuminating the scene imaged by thecamera. In an automobile, the IR illuminator assemblies may be packagedwith or near the vehicle's headlamps. Since IR radiation is notdetectable to the human eye, it is possible to substantially illuminatethe scene in front of a vehicle without any concern for glare disruptingoncoming or preceding drivers.

[0108] The camera is configured to image at least the same spectra oflight as the IR LEDs emit. Preferably, the camera's spectral sensitivityis limited by the use of filters to only the wavelength range of lightemitted by the IR LEDs. This reduces any washing-out or blooming in theimage from other light sources. The camera can be mounted to lookthrough the vehicle's windshield in the region cleaned by the vehicle'swiper and washer system by placing the camera in the mount of a rearviewmirror. The camera preferably uses a wide dynamic image sensor to allowfor imaging of both bright and faint objects in the forward scenesimultaneously. Such an image sensor is described in commonly-assignedU.S. Pat. No. 6,008,486 entitled “WIDE DYNAMIC RANGE OPTICAL SENSOR.”

[0109] If a scene rearward of the vehicle is to be imaged using such anear IR imaging system, the camera may be mounted in the centerhigh-mounted stop lamp (CHMSL) in a tail light, or behind the rearwindow, while the radiation emitting device of the present invention maybe mounted in the same location as the camera or in a different one ofthe above locations. A similar rear vision system is disclosed incommonly assigned PCT International Publication No. WO 00/15462,entitled “SYSTEMS AND COMPONENTS FOR ENHANCING REAR VISION FROM AVEHICLE,” by Frederick T. Bauer et al.

[0110] As will be appreciated by those skilled in the art, the radiationemitting device of the present invention allows for more efficientextraction of the heat generated by the radiation emitters. Thisimproved extraction allows for a greater driving current to be deliveredto the radiation emitters, which, in turn, generates higher radiationflux levels than previously obtained. The LED construction disclosed inthe commonly-assigned U.S. Pat. No. 6,335,548 discussed above, achievespower densities of up to about 2 W/in² or more while the structure ofthe present invention may obtain power densities of up to 5 to 10 W/in²or more. Certain embodiments of the present invention may be capable ofpower dissipation in excess of 1 W for miniature lamp applications(i.e., small area embodiments), and up to and exceeding 1000 W for highpower lamp applications (i.e., large area embodiments).

[0111] Additionally, the likelihood that any wire bonds utilized mayfatigue or break is either eliminated (as in the case with the firstembodiment where wire bonds are not required), or significantly reduced,since the present invention does not encapsulate these wire bonds with asolid encapsulant. Because the wire bonds used in the embodiment shownin FIGS. 4 and 5 are surrounded by a liquid or gel, shear forces cannotbe transferred to the wire bond as a result of any thermal expansion orcontraction as would be the case if they were encapsulated in aconventional encapsulant material.

[0112] A manufacturing process for making embodiments of the presentinvention comprising light engine modules first includes mountingoptional surface mount, BGA, chips or other electronic components ontothe first substrate. Next, one or more LED chips to the first substrateusing eutectic attachment, solder attachment, die-attach adhesive, epoxyor the like. Next, additional optional surface mount, BGA, chips orother electronic components may be mounted onto first substrate. Acuring stage or reflow stage is typically performed, as appropriate toform permanent electrical and mechanical bonds between chips andcomponents and the first substrate. Next, wirebonding is performed forembodiments using wirebonds for electrical connection to one or more LEDor electronic component chip. Next, a barrier adhesive, seal or gasketmaterial is placed or dispensed onto first or second substrate. The sealmaterial can optionally or additionally be pre-arranged upon or madeintegral with portions of either first or second substrate. At any pointup to this point in the process, optional spacers may be placed withinthe region subsequently forming the cavity, either by placing ormounting them on the first substrate or the second substrate or bysandwiching them between the two substrates. Next, the first and secondsubstrates are placed in close proximity such that any seal material orstructure bridges the narrow gap between them along an appropriateportion of their surfaces. To facilitate large scale manufacturing andproduction of several modules at one time or modules having severalsemi-independent chambers, several first substrates may be placed ontoone second substrate (and associated seal material) or vice versa. Sealmaterial is next cured, sintered, or melted by thermal treatment orradiation exposure such as baking, IR heating, e-beam or microwavecuring, reflow or other similar process. Small openings may be leftwithin first or second substrate or seal material to provide a channelfor subsequent filling of the cavity. Fluid may then be introduced intothe cavity by vacuum-backfill process, 2-port pressure or gravityfilling or other means. After the cavity is filled, openings in thefirst or second substrate or seal may be plugged with UV curable epoxyor other sealant/barrier material.

[0113] The above description is considered that of the preferredembodiments only. Modifications of the invention will occur to thoseskilled in the art and to those who make or use the invention.Therefore, it is understood that the embodiments shown in the drawingsand described above are merely for illustrative purposes and notintended to limit the scope of the invention, which is defined by thefollowing claims as interpreted according to the principles of patentlaw, including the doctrine of equivalents.

The invention claimed is:
 1. An optical radiation emitting devicecomprising: a sealed chamber; a liquid or gel contained in said sealedchamber; an electroluminescent emitter that emits optical radiation inresponse to an electrical signal, said electroluminescent emitterdisposed in said sealed chamber in physical and thermal contact withsaid liquid or gel; and first and second electrical conductorselectrically coupled to said electroluminescent emitter for energizingsaid electroluminescent emitter.
 2. The optical radiation emittingdevice of claim 1, wherein said liquid or gel has a relatively lowelectrical conductivity.
 3. The optical radiation emitting device ofclaim 1, wherein said electroluminescent emitter is an LED chip.
 4. Theoptical radiation emitting device of claim 1, wherein said sealedchamber is formed between first and second substrates that are spacedapart and joined by a seal.
 5. The optical radiation emitting device ofclaim 1 and further including a sensor disposed in said sealed chamber.6. The optical radiation emitting device of claim 5, wherein said sensoris an optical sensor.
 7. The optical radiation emitting device of claim5, wherein said sensor is a thermal sensor.
 8. The optical radiationemitting device of claim 1 and further including a thermistor disposedin said sealed chamber.
 9. The optical radiation emitting device ofclaim 1 and further including a resistor disposed in said sealedchamber.
 10. The optical radiation emitting device of claim 1 andfurther including a transistor disposed in said sealed chamber.
 11. Theoptical radiation emitting device of claim 1 and further including adiode disposed in said sealed chamber.
 12. The optical radiationemitting device of claim 1 and further including a Zener diode disposedin said sealed chamber.
 13. The optical radiation emitting device ofclaim 1 and further including a voltage regulator disposed in saidsealed chamber.
 14. A radiation emitting device comprising: a sealedchamber; a liquid or gel contained in said sealed chamber and having arelatively low electrical conductivity; a radiation emitter that emitsradiation in response to an electrical signal disposed in said sealedchamber in thermal contact with said liquid or gel; and first and secondelectrical conductors electrically coupled to said radiation emitter andextending out of said sealed chamber.
 15. The radiation emitting deviceof claim 14, wherein said sealed chamber is defined by first and secondsubstrates sealed together.
 16. The radiation emitting device of claim15, wherein said first substrate is a circuit board and wherein at leastone of said first and second electrical conductors are traces formed onsaid circuit board.
 17. A radiation emitting device comprising: firstand second substrates sealed together and spaced apart to define asealed chamber; a liquid or gel contained in said sealed chamber; and aradiation emitter that emits radiation in response to an electricalsignal disposed in said sealed chamber in thermal contact with saidliquid or gel.
 18. The radiation emitting device of claim 17, whereinsaid second substrate is at least partially transparent to the radiationemitted from said radiation emitter.
 19. The radiation emitting deviceof claim 18 and further including a transparent electrical conductorprovided on said second substrate.
 20. The radiation emitting device ofclaim 17, wherein said first substrate is electrically conductive. 21.The radiation emitting device of claim 17, wherein said first substratehas a high thermal conductivity.
 22. The radiation emitting device ofclaim 17, wherein said first substrate is electrically nonconductive.23. The radiation emitting device of claim 22 and further including anelectrical conductor provided on said first substrate.
 24. The radiationemitting device of claim 23 and further including a second electricalconductor provided on said first substrate.
 25. The radiation emittingdevice of claim 23 and further including a second electrical conductorprovided on said second substrate.
 26. The radiation emitting device ofclaim 17 and further including an electrical conductor provided on saidsecond substrate.
 27. The radiation emitting device of claim 17, whereinsaid liquid or gel includes propylene carbonate.
 28. The radiationemitting device of claim 17 and further including a plurality ofradiation emitters disposed in said sealed chamber.
 29. The radiationemitting device of claim 28, wherein said plurality of radiationemitters emits binary complementary colored light to form effectivewhite light.
 30. The radiation emitting device of claim 28, wherein saidplurality of radiation emitters emits red, green, and blue coloredlight.
 31. The radiation emitting device of claim 28, wherein saidplurality of radiation emitters emits light having the same hue.
 32. Theradiation emitting device of claim 17, wherein said radiation emitteremits infrared radiation.
 33. The radiation emitting device of claim 17,wherein said radiation emitter emits ultraviolet radiation.
 34. Theradiation emitting device of claim 17, wherein said first substrate is acircuit board.
 35. A method of reducing thermal resistance of aradiation emitter device, the method comprising the steps of: mountingthe radiation emitter device on a substrate; and surrounding at least aportion of the radiation emitter device with a convective liquid or gel.36. The method of claim 35, wherein said substrate has a high thermalconductivity.
 37. The method of claim 35, wherein said step ofsurrounding the radiation emitter device with a liquid or gel includesthe substeps of: providing a first substrate; mounting the radiationemitter device to the first substrate; sealing a second substrate to thefirst substrate to define a sealed chamber around the radiation emitterdevice; and dispensing the liquid or gel in the sealed chamber.
 38. Themethod of claim 35, wherein said liquid or gel is highly convective. 39.A vehicle headlamp comprising: a sealed chamber; a liquid or gelcontained in said sealed chamber; a plurality of optical radiationemitters that emits light in response to an electrical signal, saidlight sources disposed in said sealed chamber in physical and thermalcontact with said liquid or gel; and first and second electricalconductors electrically coupled to said optical radiation emitters forenergizing said optical radiation emitters.
 40. A package for at leastone electronic semiconductor component, said package comprising: firstand second substrates sealed together and spaced apart to define asealed chamber; a liquid or gel contained in said sealed chamber; and atleast one electronic semiconductor component disposed in said sealedchamber in thermal contact with said liquid or gel.
 41. The electroniccomponent package of claim 40, wherein said first and second substratesare printed circuit boards.
 42. The electronic component package ofclaim 40, wherein said second substrate is substantially opaque.
 43. Theelectronic component package of claim 40, wherein said second substrateis substantially transparent.
 44. The electronic component package ofclaim 40, wherein said at least one electronic component includes aradiation emitting device.
 45. The electronic component package of claim40, wherein said at least one electronic component includes an opticalsensor.
 46. The electronic component package of claim 40, wherein saidat least one electronic component includes a microprocessor.
 47. Theelectronic component package of claim 40, wherein said second substratehas a high thermal conductivity.
 48. The electronic component package ofclaim 40, wherein said first substrate is a printed circuit board. 49.The electronic component package of claim 48, wherein a portion of saidfirst circuit board extends outward from said sealed chamber, saidportion including at least one electrical contact electrically coupledto at least one of said electronic components disposed in said sealedchamber.
 50. The electronic component package of claim 49, wherein saidelectrical contact is configured to contact a corresponding electricalcontact in an edge connector.
 51. The electronic component package ofclaim 40, wherein said second substrate is a heat sink having a largeouter surface area.
 52. The electronic component package of claim 51,wherein said heat sink having a plurality of fins extending away fromsaid sealed chamber.
 53. The electronic component package of claim 51,wherein said heat sink having a plurality of passageways through whichliquid may flow.
 54. The electronic component package of claim 53,wherein said passageways open into said sealed chamber such that saidliquid in said sealed chamber may flow through said passageways.
 55. Apackage for at least one electronic component, said package comprising:a circuit board and a substrate, sealed together and spaced apart todefine a sealed chamber; a liquid or gel contained in said sealedchamber; and at least one electronic component mounted on said circuitboard and disposed in said sealed chamber in thermal contact with saidliquid or gel.
 56. The electronic component package of claim 55, whereinsaid substrate is substantially opaque.
 57. The electronic componentpackage of claim 55, wherein said substrate is substantiallytransparent.
 58. The electronic component package of claim 55, whereinsaid at least one electronic component includes a radiation emittingdevice.
 59. The electronic component package of claim 55, wherein saidat least one electronic component includes an optical sensor.
 60. Theelectronic component package of claim 55, wherein said at least oneelectronic component includes a microprocessor.
 61. The electroniccomponent package of claim 55, wherein said at least one electroniccomponent includes a resistor.
 62. The electronic component package ofclaim 55, wherein said second substrate has a high thermal conductivity.63. The electronic component package of claim 55, wherein said at leastone electronic component includes a semiconductor component.
 64. Anoptical radiation emitting device comprising: first and secondsubstrates sealed together and spaced apart to define a sealed chamber;a liquid or gel contained in said sealed chamber; a plurality 6f LEDchips secured to said first substrate; and first and second electricalconductors disposed on one or both of said first and second substratesand electrically coupled to said LED chips for energizing said LEDchips.
 65. An optical radiation emitting device comprising: a sealedchamber; a fluid intermediary material contained in said sealed chamberand having a refractive index greater than 1.0; an electroluminescentemitter that emits optical radiation in response to an electricalsignal; said electroluminescent emitter disposed in said sealed chamberin physical and thermal contact with said fluid intermediary material;and first and second electrical conductors electrically coupled to saidelectroluminescent emitter for energizing said electroluminescentemitter.
 66. The optical radiation emitting device of claim 65, whereinsaid fluid intermediary material contained has a refractive indexgreater than about 1.3.
 67. The optical radiation emitting device ofclaim 65, wherein said fluid intermediary material contained has arefractive index greater than about 1.4.
 68. The optical radiationemitting device of claim 65, wherein said fluid intermediary medium is aliquid or gel.
 69. An optical radiation emitting device comprising: asemiconductor radiation emitter that emits optical radiation in responseto an electrical signal; a protective barrier for protecting saidsemiconductor radiation emitter, said protective barrier comprises amaterial that substantially maintains its in-band optical propertiesover time; and first and second electrical conductors electricallycoupled to said semiconductor radiation emitter for energizing saidsemiconductor radiation emitter.
 70. The optical radiation emittingdevice of claim 68, wherein said protective barrier is made of amaterial that is resistant to yellowing over time.
 71. The opticalradiation emitting device of claim 68, wherein said protective barrieris made of a material that is resistant to hazing.
 72. The opticalradiation emitting device of claim 68, wherein said protective barrieris made of glass.
 73. The optical radiation emitting device of claim 68,wherein said protective barrier comprises a substrate and anintermediary material disposed between said emitter and said substrate.